In a conventional patterning process for semiconductor device fabrication, after a photoresist pattern is formed on a predetermined film to be etched for pattern formation, for example, a silicon film, a dielectric film, or a conductive film, the predetermined film may be etched by using the photoresist pattern as an etching mask to form a desired pattern.
With the increased integration of semiconductor devices, it is desirable to have a design rule of smaller critical dimension (CD) as well as lithography technology suitable for forming fine patterns including contact holes having a smaller opening size or spaces with a smaller width.
In a conventional lithography process for forming smaller-sized contact holes, short-wavelength exposure techniques such as E-beam lithography or a half-tone phase shift mask may be used. Short-wavelength exposure based lithography may present difficulties in that this process can be material-dependent and uneconomical. In particular, half-tone phase shift mask based lithography may pose limitations on mask formation technology and resolution, and thus, it may be difficult to form contact holes which are less than 150 nm in size.
Thus, various techniques for achieving smaller feature sizes have been suggested. For example, Japanese Patent Laid-Open Publication No. 1989-307228 discusses a technique for forming a fine resist pattern in which a resist pattern formed by exposure and development of a resist film is thermally treated so that the profile shape of the resist pattern is altered.
Japanese Patent Laid-Open Publication Nos. 1993-241348, 1994-250379, 1998-73927, 1999-204399, 1999-283905, 1999-283910, 2000-58506, 2000-298356, 2001-66782, 2001-228616, 2001-19860, and 2001-109165 discuss a method of forming a fine resist pattern by a chemical treatment process. In particular, Japanese Patent Laid-Open Publication No. 2001-228616 discusses a technique for decreasing a hole diameter and an isolation width of a resist pattern by increasing the thickness of the resist pattern. According to this technique, the resist pattern that can serve as an acid donor is coated with a framing material that is capable of being crosslinked with the acid. Further, when the acid is transferred from the resist pattern to a layer including the framing material by heating, a crosslinked layer is formed as a layer covering the resist pattern at an interface between the resist pattern and the framing material layer.
Japanese Patent Laid-Open Publication Nos. 2003-107752, 2003-84448, 2003-84459, 2003-84460, 2003-142381, 2003-195527, 2003-202679, 2003-303757, and 2003-316026 discuss a composition for fine pattern formation and a pattern formation method. In particular, Japanese Patent Laid-Open Publication No. 2003-202679 discusses a method of forming fine patterns using a coating agent. The coating agent is coated on a substrate having photoresist patterns in order to decrease spacing between the photoresist patterns caused, at least in part, by the thermal shrinkage effect of the coating agent.